Method for making advanced smart cards with integrated electronics using isotropic thermoset adhesive materials with high quality exterior surfaces

ABSTRACT

Advanced Smart Cards and similar form factors (e.g. documents, tags) having high quality external surfaces of Polyvinylchloride (PVC), Polycarbonate (PC), synthetic paper or other suitable material can be made with highly sophisticated electronic components (e.g. Integrated Circuit chips, batteries, microprocessors, Light Emitting Diodes, Liquid Crystal Displays, polymer dome switches, and antennae), integrated in the bottom layer of the card structure, through use of injection molded thermosetting or thermoplastic material that becomes the core layer of said Advanced Smart Cards. A lamination finishing process can provide a high quality lower surface, and the encapsulation of the electronic components in the thermosetting or thermoplastic material provides protection from the lamination heat and pressure.

BACKGROUND OF THE INVENTION

The present invention relates generally to advanced smart cards that maycontain batteries, LEDs, LCDs, polymer dome switches, fingerprintsensors, and other electronic components that are not found inconventional smart cards. A conventional smart card is the size of atraditional credit card, and they usually contain an Integrated Circuit(IC) chip and may contain an antenna if the card must transfer datausing Radio Frequency (RF) transmission. Advanced smart cards mayinclude components that are not found in conventional smart cards, suchas batteries, displays, and keypads. Advanced smart cards may thereforebe capable of many sophisticated functions, such as displaying data,enabling users to enter Personal Identification Numbers (PIN) andpasswords, and detecting security threats.

Smart cards are being widely utilized for access control systems,storage of biometric data, national border control, and in many otherapplications. Smart cards typically contain information about a user.For example, the U.S. Department of Defense (DoD) Common Access Card(CAC) project requires a contactless chip to contain biometric dataabout a citizen including a digitized portrait and fingerprint data.

These advanced smart cards typically consist of a multi-layer structurehaving one or more plastic layers surrounding integrated circuits thatstore the data. Data is transferred to and from the cards through radiofrequency (RF) transmission. Cards that transfer data only by RFtransmission are so-called “contactless” cards. For RF transmission,contactless advanced smart cards include an antenna for transmittingdata to and from the integrated circuits. With increasing securityconcerns in the post-September 11 environment, contactless RFID chipsare being incorporated into documents like passports and other documentor note formats.

Several problems exist with prior art smart card arrangements in thatPVC is utilized for its rigidity in order to protect the antenna andintegrated circuit from breaking upon flexure. Each layer of PVC must beof a prescribed thickness to surround and protect the components. Inorder to maintain the rigidity required and house the componentsnecessary, these PVC cards tend to be relatively thick as compared toother types of cards such as a credit card. Generally, such resultingmulti-layer structures are approximately 0.060 inches thick.Additionally, PVC tends to become brittle with age and exposure toultraviolet rays. This contributes to card failure in time.Additionally, specialized printing equipment is required to printinformation on the outer surfaces of the PVC material.

Many other problems frequently occur with the very high temperatures andpressures required for hot lamination including damage to fragileIntegrated Circuit (IC) chips, antenna (often thin wire coils, thinlyetched copper, or thinly deposited silver), and other electroniccomponents. The very high heat levels, typically about 300° F., and thevery high pressures, typically ranging from 1,000 to 30,000 PSI orgreater, used in the plastic card lamination production process are thecause of severe thermal and physical stress on smart card components.

What is needed is an improved method for producing an Advanced SmartCard (containing Integrated Circuits, antennae, batteries, polymer domeswitches, Liquid Crystal Displays, Light Emitting Diode arrays,fingerprint sensors), that allows sensitive components to be securelyand reliably incorporated into a very thin and flexible card structure,and that utilizes low heat (e.g. less than 150° F.) and low pressure(e.g. less than 100 PSI).

A new generation of highly sophisticated smart cards has becometechnically feasible due to advances in materials science andelectronics. Miniature batteries, data displays, keypads, and evenfingerprint sensors have been developed that may be incorporated into asmart card sized form factor. These advances are stimulating new smartcard capabilities and applications. For example, a smart card equippedwith a battery, data display, and keypad would enable users to view dataregarding: 1) the current balance of electronic purse applications, 2)recent credit card transaction information, or 3) bank account balanceinformation. These capabilities could also be utilized to enhancesecurity with password-enabled credit card functions. While theseexpanded smart card capabilities offer tremendous potential for newapplications, large scale production of advanced cards withlamination-based manufacturing techniques is extremely difficult due tothe electronic component damage caused by the high heat and pressureused in lamination. A new card production process utilizing low heat andpressure is needed to enable delicate electronic components to beeffectively incorporated within card bodies.

SUMMARY OF THE INVENTION

It is therefore an object of this invention to provide an Advanced SmartCard with a thickness not greater than 0.80 mm (the thickness of aconventional credit card) that contains securely encapsulated AdvancedSmart Card electronics that may include: Integrated Circuits, antennae,batteries, polymer dome switches, Liquid Crystal Displays, LightEmitting Diode arrays, fingerprint sensors.

This and other objects are achieved by providing a multi-layer cardstructure with a top layer of material such as synthetic paper, PVC, PC,or other suitable material, a bottom layer that is comprised of anintegrated electronics assembly (that may include Integrated Circuits,antennae, batteries, polymer dome switches, Liquid Crystal Displays,Light Emitting Diode arrays, and fingerprint sensors), with a core layerof injected polymeric material that securely encapsulates the electroniccomponents that make up the bottom layer, and securely bonds to the toplayer of synthetic paper or other suitable material.

The void space between the top layer and the bottom layer facilitates aneven flow and a complete encapsulation of the electronic components byinjected polymeric material. The void space of approximately 0.1 to 0.25mm allows injected polymer to fill the void space and cover theelectronic components and the bottom surface of the top layer, with novoids, pockets and with an even and complete distribution of thepolymeric material in the void space.

The integrated electronics assembly that makes up the bottom layer isproduced on a single continuous sheet, which is then cut by a machinetool in a form that allows the Advanced Smart Card perimeter to becovered by the injected polymer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away side view of an Advanced Smart Card made accordingto the teachings of this patent disclosure.

FIGS. 2 and 3 are cut-away side views of a mold tool set up for making afirst preferred embodiment of an Advanced Smart Card of this patentdisclosure wherein certain Advanced Smart Card components (e.g.Integrated Circuit chips and antenna coil) are shown before a liquidpolymeric material is injected between the Advanced Smart Card's top andbottom layers (see FIG. 4 and after (see FIG. 5) the polymeric materialis injected into a void space between the top and bottom layers andthereby filling said void space with a polymeric material and coldforming the top layer of the Advanced Smart Card to the contour of thetop mold's document-forming cavity.

FIG. 4 is a cut-away view showing a mold tool being removed from aprecursor Advanced Smart Card body formed by the system generallydepicted in FIG. 3.

FIG. 5 depicts a mold tool system that is capable of making six AdvancedSmart Cards (with dimensions of approximately 54 mm by 85 mm)simultaneously.

FIG. 6 illustrates a cut-away view of a Contacted Advanced Smart Cardmade according to the teachings of this patent disclosure.

FIG. 7 illustrates a cut-away view of a Contactless Advanced Smart Cardmade according to the teachings of this patent disclosure.

FIG. 8 illustrates a cut-away view of a Dual Interface Advanced SmartCard made according to the teachings of this patent disclosure.

FIG. 9 illustrates a cut-away view of a Dual Interface Advanced SmartCard with a Fingerprint Sensor 30 made according to the teachings ofthis patent disclosure.

FIG. 10 illustrates a cut-away view of a Chemosensitive Advanced SmartCard with a Sensor Strip 37 that is chemically reactive and provides avisual signal when particular chemical substances or radiation has beendetected. The heat-sensitive Sensory Strip is protected from hightemperature deterioration by the low-temperature, low-pressure processused with the card manufacturing method in this disclosure.

FIG. 11 illustrates a cut-away view of a Contactless Advanced Smart Cardwith an Acoustic Speaker 73 made according to the teachings of thispatent disclosure.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 depicts a cut-away side view of an Advanced Smart Card 22 madeaccording to the teachings of this patent disclosure. In its finishedform, such an Advanced Smart Card will be comprised of a top layer 24, abottom layer 26, and a center or core layer 28.

The top layer 24 is a film or sheet of synthetic paper PVC,Polycarbonate, or other suitable material. The bottom layer 26 is anelectronics assembly on substrate circuit board (e.g. polyimide forflexible printed circuits or industry standard FR4 for conventionalprinted circuit boards) containing a number of integrated electroniccomponents such as a Light Emitting Diode (LED) 30, a battery 32, apolymer dome switch 33, a microprocessor 35, an antenna 31, a LiquidCrystal Display (not shown). The center or core layer consists of athermosetting polymeric material 34 (e.g., an initially liquid orsemi-liquid thermosetting resin) that, upon curing, constitutes thecenter or core layer 28 of a finished Advanced Smart Card. The center orcore layer 28 completely encapsulates all exposed electronic componentson the top surface of the bottom layer 26. The thermosetting material 34that eventually becomes the center layer 28 of the Advanced Smart Cardis injected into the void space 36 between the top layer 24 and bottomlayer 26. This injected polymeric material 34 should be capable of beinginjected under the relatively cold, low pressure forming conditionsemployed in applicant's process.

In any case, such thermosetting polymeric materials will be injectedinto, and fill, the void space 36 defined between the inside surface 38of the top layer 24 and the inside surface 40 of the bottom layer 26.Upon curing, the polymeric material 34 of the center layer 28 shouldbond or otherwise adhere to both the inside surface 38 of the top layer24 and the inside surface 40 of the bottom layer 26 to produce a unifiedAdvanced Smart Card body. Such adhesion can be aided by treating theinside surfaces 38 and 40 of the top and bottom layers, respectively, inany one of several ways.

For example, bond promoting agents known to this art (e.g.chloro-polyolefins) may be employed to enhance bonding between the corelayer-forming thermoset material and the material(s) from which the topand bottom layers are made (e.g., PVC, polyimide). By way of exampleonly, Minnesota Mining and Manufacturing's base primer product 4475.RTMcan be used for this bond enhancing purpose, especially when the top orbottom layer material is PVC. Other treatments that can be applied tothe inside surfaces of the top and/or bottom layers include plasmacorona treatments and acid etching.

The Advanced Smart Card's thickness 39 is defined by placement of themold faces (not shown in FIG. 1) as the thermoset material is injectedinto the void space 36 as part of the cold, low pressure forming processof this patent disclosure. In effect, the injection of the thermosetmaterial into the void space 36 between the top and bottom layers fillsany portion of that void space 36 that is not otherwise occupied by theelectronic components protruding from the bottom layer 26.

The layout of electronic components on the top surface of the bottomlayer in the manner generally suggested in FIG. 2 allows the incomingliquid or semi-liquid polymeric material to flow over and around allsides of exposed electronic components.

The elastomeric properties of the cured thermoset polymer provideprotection from physical and thermal stressors for the electroniccomponents in the bottom layer. The shock-absorbing properties of theelastomer that encapsulates all exposed electronics enable the assemblyto resist flexion and/or torsion and/or impact forces that the AdvancedSmart Card may encounter upon either of its major outside surfaces or onany of its four outside edge surfaces. The thermal insulation propertiesof the elastomer also reduce the amount of heat to which the electroniccomponents may be exposed during a final hot lamination processemploying a thin layer of PVC to create a high quality exterior surfaceon the bottom surface of the bottom layer.

FIGS. 2 and 3 are contrasted to illustrate a first preferred embodimentof applicant's methods for making Advanced Smart Cards.

That is to say that FIG. 2 depicts a particularly preferred embodimentof this invention wherein a flat, top layer or sheet 24 of syntheticpaper or plastic material such as PVC is shown before it is cold, lowpressure formed according to the teaching of this patent disclosure. Inother words, FIG. 2 depicts the mold tool set-up just prior to theinjection of the polymeric material and wherein a flat, top layer 24(e.g., a flat sheet of PVC) is shown as it is initially placed under anAdvanced Smart Card-forming cavity of the top mold 44 and a bottom layer26 (e.g., an integrated electronics assembly on a substrate) is shown asit is placed over a bottom mold 46. Again, however, in someless-preferred, but still viable, embodiments of applicant's processesthe top layer 24 may be pre-molded or at least partially pre-molded,preferably, to the general contour of the Advanced Smart Card-formingcavity 64 in the top mold. By way of comparison, the bottom mold 46 hasno cavity comparable to the cavity in the top mold 44. A nozzle 48 forinjecting a liquid or semi-liquid, thermoplastic or thermosettingpolymeric material 34 is shown being inserted into an orifice 49 thatleads to the void space 36 that is defined between the inside surface 38of the top layer 24 and the inside surface 40 of the bottom layer 26.The distance between the top surface of the top layer and the bottomsurface of the bottom layer of the Advanced Smart Card is depicted bydistance 39. The void space 36 is shown extending from the left end tothe right end of the juxtaposed top layer 24 and bottom layer 26. Inother words, in FIG. 2 the outside surface 55 of the top layer 24 is notyet in contact with the inside surface 56 of the Advanced SmartCard-forming cavity 64 of the top mold 44. By way of contrast, theoutside surface 58 of the bottom layer 26 is shown in substantiallyflat, abutting contact with the inside surface 60 of the bottom mold 46.FIG. 3 depicts the effects of injecting the thermoset polymeric materialinto the void space 36 between the top and bottom layers 24 and 26.Thus, FIG. 3 shows the top layer 24 after it has been molded into anAdvanced Smart Card-forming cavity 64 in the top mold 44.

In both FIGS. 2 and 3 the electronic components contained in the bottomlayer 26 of the Advanced Smart Card (e.g., the antenna 31, battery 32,IC chip 35) are shown as they may be positioned in the integratedelectronics assembly comprising the bottom layer. This invention forproducing Advanced Smart Cards is compatible and viable for a wide rangeof card designs that incorporate a variety of components and devices inthe bottom layer. The detailed design of the electronic components inbottom layer 26 will depend on the specific application(s) for which theAdvanced Smart Card is intended. These applications may include: accesscontrol for building entry, data display for bank cards or ATM cards,password entry for Identification Cards, and fingerprint verification(using a fingerprint sensor) for security-related applications.

For the purpose of this invention, the detailed design of the circuitand electronic components in bottom layer 26 is not critical except forthe dimensional constraints that must be satisfied. For an ISO7810-compliant Advanced Smart Card produced using this method, theelectronic elements in the bottom layer must fit within a form factor of81 mm (length) by 49 mm (width) and with a maximum height of 0.55 mm(including the bottom layer substrate). The distance 43 in FIG. 3 isabout 0.15 mm and it represents the minimum clearance from the insidesurface 38 of the top layer 24 and the top-most surface of the highestelectronic component 30 mounted on the bottom layer 26. The minimumdistance 43 is required to allow sufficient injected polymeric materialto encapsulate the electronic components mounted on the bottom layer andto provide adequate shock-absorption and thermal insulation properties.

In FIG. 2 the top mold 44 is shown having a cavity 64, which defines thesurface contour of the top of the Advanced Smart Card to be formedduring the injection process. To this end, the injection of the liquidor semi-liquid thermoset polymeric material 34 should be under pressureand temperature conditions such that the top layer 24 is cold, lowpressure, formed into the cavity 64 of the top mold 44. FIG. 3 shows howthe cold, low pressure forming process of this patent disclosure has infact conformed the top surface 55 of the top layer 24 to theconfiguration of the Advanced Smart Card-forming cavity 64 in the topmold 44. Again, the bottom surface 58 of the bottom layer 26 is shown inFIG. 3 molded against a substantially flat inside surface 60 of thebottom mold 46. This is a particularly preferred arrangement for makingthe Advanced Smart Cards of this patent disclosure.

In FIGS. 2 and 3 a front lip region 66 of the top mold 44 and a frontlip region 68 of the bottom mold 46 are shown spaced apart from eachother by a distance 70 that (taking into consideration the thickness ofthe top and bottom layers 24 and 26), in effect, defines the distance 36(i.e., the width of the void space) between the top layer 24 and thebottom layer 26 at these lip regions of the two molds 44 and 46. Thisdistance 70 should be such that the thermoset polymeric material 34 canbe injected into the void space 36 over the entire length of theAdvanced Smart Card (e.g., from its left side to its right side). Thecounterpart distance 70′ of the mold device setting on the right side ofthe system shown in FIG. 2 may differ from that of its counterpartdistance 70 on the left side. In any case the distance 70′ should besuch that the distance 36′ defined between the inside surface 38 of thetop layer 24 that passes through the rear lip 66′ of the top mold 44 andthe inside surface 40 of the bottom layer 26 that passes through therear lip 68′ of the bottom mold 46 is very small—but still finite. Thatis to say that this very small distance 36′ should be large enough toallow gases 72 (e.g., air, polymeric ingredient reaction product gases,etc.) in the void space 36 that originally existed between the top andbottom layers 24 and 26 (see again, FIG. 2) and excess polymericmaterial to be exhausted from said void space 36, but still be smallenough to hold the injection pressures used to inject the thermosetpolymeric material. Indeed, the distance 36′ is preferably sized largeenough to allow even thin layers of the liquid polymeric material 34itself to be “squirted” or “flashed” out of the void space 36—and thusallowing all gases residing in, or created in, the void space 36 to beexpunged out of said void space and, indeed, out of the mold systemitself. Thus, all such gases 72 are completely replaced by the incomingliquid thermoset material 34. This gas exhaust technique serves toprevent gas bubbles from forming in the body of the thermoset material34 that eventually (i.e., upon curing of the thermoset material)comprises the center layer 28.

FIG. 4 shows a semi-finished or precursor Advanced Smart Card of thetype shown in FIG. 3 being removed from a mold system. Section lines84-84 and 86-86 respectively show how the left end and right end of theprecursor Advanced Smart Card can be cut or trimmed away to create thesharp edges and precise dimensions of a finished Advanced Smart Card. Inthis case the distance 74 is about 85 millimeters to conform to ISO 7810specifications for an Identification Card.

FIG. 5 illustrates a molding procedure being carried out according tosome of the preferred embodiments of this patent disclosure wherein sixAdvanced Smart Cards with dimensions of approximately 85 mm by 54 mm arebeing molded simultaneously.

FIG. 6 illustrates a completed contacted Advanced Smart Card madeaccording to the teachings of this patent disclosure.

FIG. 7 illustrates a completed contactless Advanced Smart Card madeaccording to the teachings of this patent disclosure.

FIG. 8 illustrates a dual interface Advanced Smart Card made accordingto the teachings of this patent disclosure.

FIG. 9 illustrates a dual interface Advanced Smart Card with fingerprintsensor 30 made according to the teachings of this patent disclosure.

FIG. 10 illustrates a chemosensitive Advanced Smart Card with a sensorstrip 37 that is chemically reactive and provides a visual signal whenparticular chemical substances or radiation has been detected. Theheat-sensitive sensor strip is protected from high-temperaturedeterioration by the low-temperature, low-pressure process used with thecard manufacturing method in this disclosure.

FIG. 11 illustrates a contactless Advanced Smart Card with an acousticspeaker 73 made according to the teachings of this patent disclosure.

While this invention has been described with respect to various specificexamples and a spirit that is committed to the concept of the use ofspecial glues and gluing procedures, it is to be understood that thehereindescribed invention should be limited in scope only by thefollowing claims.

1. A method for making an advanced smart card comprising a top layer, acore layer of thermoset polymeric material, and a bottom layercomprising an integrated electronics assembly mounted on a substrate,said method comprising: (1) positioning a bottom layer comprising theintegrated electronics assembly mounted on a substrate in a bottom mold(2) positioning a top layer comprising synthetic paper or other plasticmaterial in a top mold; (3) closing the top mold to the bottom mold in amanner that creates a void space between the top layer and the bottomlayer comprising the integrated electronics assembly; (4) injecting athermosetting polymeric material into the void space to form a corelayer of polymeric material, the injection taking place at a temperatureand pressure which are such that: (a) the top layer of material is atleast partially cold, low pressure molded into a cavity in the top mold;(b) gases and excess polymeric material are driven out of the voidspace; (c) the injected polymeric material flows over and around allexposed portions of the electronic components of the integratedelectronic assembly positioned on the top surface of the bottom layersuch that the bottom surface of the bottom layer remains free of theinjected polymeric material; and (d) the thermosetting polymericmaterial bonds with both the top layer and the bottom layer to produce aunified precursor advanced smart card body; (5) removing the unifiedprecursor advanced smart card body from the top and bottom molds; and(6) trimming the precursor advanced smart card to a desired dimension toproduce a finished advanced smart card.
 2. The method of claim 1,wherein the integrated electronics assembly mounted on a substrate hasmaximum dimensions of 54 mm high, 85.6 mm long, and 0.50 mm thick. 3.The method of claim 1, wherein the substrate is a printed circuit board.4. The method of claim 1 wherein the inside surface of the top layer andthe inside surface of the bottom layer are treated to facilitate thecreation of a strong bond between the top layer and the thermosettingmaterial and the bottom layer and the thermosetting material.
 5. Themethod of claim 1 wherein the inside surface of the top layer and theinside surface of the bottom layer are treated by coating each with abond promoting agent.
 6. The method of claim 1 wherein the insidesurface of the top layer and the inside surface of the bottom layer aretreated by a corona discharge process.
 7. The method of claim 1 whereinthe thermosetting polymeric material is injected into the void space ata pressure less than 100 psi.
 8. The method of claim 1 wherein thethermosetting polymeric material is injected into the void space at atemperature less than 100° F.
 9. The method of claim 1 wherein theintegrated electronics assembly includes electronic components selectedfrom the following group: microprocessors, antennae, Integrated Circuit(IC) chips, batteries, Light Emitting Diodes (LED), Liquid CrystalDisplays (LCD), polymer dome switches, acoustic speakers, and sensors(such as fingerprint sensors).
 10. The method of claim 1 wherein the toplayer is formed from a flat sheet of polymeric material.
 11. The methodof claim 1 wherein the top layer is preformed with at least onecard-forming cavity.
 12. The method of claim 1 wherein the top layer ismolded into an advanced smart card forming cavity of a top mold and thebottom layer is molded against a substantially flat surface of a bottommold.
 13. A method for making an advanced smart card comprising a toplayer, a core layer of thermoset polymeric material, and a bottom layercomprising an integrated electronics assembly mounted on a substrate,said method comprising: (1) using an integrated electronics assemblymounted on a substrate, with maximum dimensions of 54 mm wide, 85.6 mmlong, and 0.50 mm thick, and positioning the integrated electronicsassembly mounted on a substrate in a bottom mold; (2) positioning a toplayer comprising synthetic paper or other plastic material in a topmold; (3) closing the top mold to the bottom mold in a manner thatcreates a void space between the top layer and the bottom layercomprising the integrated electronics assembly; (4) injecting athermosetting polymeric material into the void space to form a corelayer of polymeric material, the injection taking place at a temperatureless than 150° F. and pressure less than 100 PSI which are such that:(a) the top layer of material is at least partially cold, low pressuremolded into a cavity in the top mold; (b) gases and excess polymericmaterial are driven out of the void space; (c) the injected polymericmaterial flows over and around all exposed portions of the electroniccomponents of the integrated electronics assembly positioned on the topsurface of the bottom layer such that the bottom surface of the bottomlayer remains free of the injected polymeric material; and (d) thethermosetting polymeric material bonds with both the top layer and thebottom layer to produce a unified precursor advanced smart card body;(5) removing the unified precursor advanced smart card body from the topand bottom molds; and (6) trimming the precursor advanced smart card toa desired dimension to produce a finished advanced smart card.
 14. Themethod according to claim 1 wherein an outside surface of the substrateupon which the electronics assembly is mounted forms an outer surface ofthe advanced smart card.
 15. The method according to claim 13 wherein anoutside surface of the substrate upon which the electronics assembly ismounted forms an outer surface of the advanced smart card.